Sound amplifier



W. F. LUHNOW.

SOUND AMPLIFIER.

APPLICATION FILED mm. 1, 1920.

1 ,420,7 1 9 Patented June 27, 1922.

UNITED STATES PATENT OFFICE.

WALTER F. LUHNOW, OF OAK PARK. ILLINOIS.

SOUND AMPLIFIER.

Specification of Letters Patent. Patented June 27, 1922,

Application filed March 1, 1920. semi No. 362,245.

fiers, of which the following is a specification.

I This invention relates to means for modulating and amplifying sound, as for instance, in sound recording devices and especially in phonographs. It follows in a large measure the lines of my copending applications, Serial No. 349,444 filed January 5, 1920. and Serial No. 357,300 filed February 9, 1.920, but is distinct therefrom particularly respecting the structure of the amplifying chamber or born.

The main objects of the invention are to provide for enriching the tones to be recorded or reproduced; to provide amplifying means of imroved form in connection with sound rccorc ers and reproducers to selectively pick up and amplifythe tones and qualities desired: and to provide such a de vice adapted for use in various forms in combination with a recorder or reproduccr, either in a cabinet or apart therefrom.

An illustrative embodiment of this invention is shown in the accompanying drawings, in which- Fig. 1 is a view of a complete phonograph partly in side elevation with the upper part in vertical section through the center from front t back.

Fig. 2 is substantially a horizontal section through the branched end of the amplifying chamber on the line 2-2 of Fig. 1.

Fig. 3 is an underside view of a modified form of branched amplifying chamber.

Fig. 4 is similar to Fig. 3 except as to the form and arrangement of the branches.

Fig. 5 is an axial section through a modified form of amplifying chamber or circular cross-section with branches distributed about the main axis, and the sound admission tube being connected directly opposite the end of the inner part of the chamber.

Fig. 6 is a section on the line 66 of Fig. 5.

Fig. 7 is a front elevation of the sound discharge end of the amplifying chamber.

Fig. 8 is an axial section of a bell-shaped chamber having a stepped inner wall.

Fig. 9 is a side elevation of a born with a medial sound inlet and with open-ended amplifying branchesshownin dotted lines.

In the constructionshown .in Fig. 1, the reproducer 1 is carried by. a pivotally mounted arm 2 communicating with the. amplifying chamber or horn 3, said parts being mounted in a cabinet 4.

Said chamber 3 is of oblong shape and for convenience and savin of space .in mounting in the cabinetis' olded medially, the large wide-mouthed end 5 being disposed above the small end 6... Thepoint of communication for said arm2 and chamber 3 is at 7 on the side of the large .end 5 near the central point or bend of said. chamber.

The lower part-pr smaller. end 6' of said chamber is branched or furcated as shown, for instance, in Fig. 2. In this instance, there are two main mutually .complementary branches 8 extending from the curved middle part of the chamber. Each;

branch 8 is forked centrally,- branches 9 be-:

ing provided as shown. 'Said branches--9 in turn are forked centrally, wherebyiiurthee.

2 i 80 In the form of amplifyingchamber branches 10 areiprovided.

shown in Fig. 3, the born 12 has a small end 13 and a large end 14.. The small end comprises two mutually com plementary; branches 1 a 1?), each f which is provided with a series of smaller branches 16, ranginginilength from very short branches to branches 'of nearly the full length of the'arms 15.

In the form shown in Fig. 4. the small end 1.? of the amplifying chamber is also l'urcated. the large end 18 being like the above described parts 5 and 14. The branches in this instance are successive, that is to say, first there are two large complementary branches 19, here shown as similar, each of which in turn divides into a pair of complementary branches 20; then again each branch 20 divides into a pair of complementary branches 21. The horns shown in Figs. 1, 2, 3 and 4 may all be similar fexeept as above specified.

In the form shown in FigsL5, 6 and 7, i

divided by radial partitions 28, which may extend the full length of the wall 25. The concentric sound chambers or parts of the one continuous chamber constitute substantially a flaring amplifier, nearly closed at the annular end 29 and wide open at the opposite end 26. This structure is substantially of a similar acoustic character with the branched horns shown in Figs. 2, 3 and 4, but differs structurally in that in this instance thesmallbranched end of the horn is disposfed concentrically about the large end of the horn instead of only at one side thereof.

In the-form shown in Fig. 8, the structure of the amplifying chamber as a whole isbel'l-shaped and more nearly resembles the form-shown in Fig. 5 than an r other embodiment here illustrated. In t is instance, the larger end of the chamber is enclosed by a flaring wall 30 outside of which is disosed the branched smallendof the amplichamber. The outer wall 30 of'the IESlII'lCiZG'Cl part of the chamber is also of: hell shape, but is less flariim than the inner wall 30, so that the radial epth of the amplifying chamberas a whole diminishes from the large main sound outlet end 32 inward to inward somewhat the open tip shown at 34.

The sound inlet tube 35 is connected to the outer'wall 31 coaxially therewith and extends past the adjacent edge of the inner wall 30. The inner end of said tube is flared somewhat as at 36, and the outer end communicates with the reproduce'r substantially as shown in Fig. 1. The inner wall is formed with a series of circumferential steps 37, each of cylindrical shape, and connected by a radial web part 38 to the-next adjacent step, so that the inner or large area end of the chamber is enclosed by a wall having outwardly facing shoulders, and the more restricted outwardly disposed small end ofthe chamber is provided with similar shoulders 39 facinE'inwardl'y, asa result of which all sound vi rat/ion is reflected and urged toward the-discharge end or mouth 32 of the main central" part of the chamber.

Any vibration or impelliug action which may occur, due to the facing of the shoulders or steps 37' and 39 will be in a like direction, that is to say, from the small end 34 inward and thence out at the large the point of'curvature 33 and then" out to Fig. 9, the elongawhich is open at end 43, the sound inlet 44 being medial and about opposite of the shortest chamber furca Other furcations vary in length,' the outermost and longest 46 being nearly the inner end tion 45.

thefulllength of the horn. I, I V In each of the forms shown, stops or plugs 47 may be nection with "'Fig. 2, as may lde desired'. at times. This assortment [of amplifying branches and stops therefor ties and tones'desired.

Although several'specific embodiments. of this invention are .lierein shown and .described, it is' to be understood" that mear the details of the constructions shown may be altered or omitted without "departi from the 's'pinit'ofthis invention as define by the following claims. i

I claim: 1. A sound amplifying long shape, mainl at the smaller end:v the large end and one of more of the branch tips being'open.

chamber. of ob discharge end 42 rovided to close one or, more of the furcation t ps as shown in con- 7 h permits s'electii'epicking up and amplification of'the; 1i 1 ali conoidal', .and fui'cated.

2. A sound amplifying. chamber of.ob

long shape, mainly at the smaller end, the large end and one or more of the branch tips bei open, and a side aperture bein provided medially to admit the sound to be amplified. 1

3. A. sou'fr'id amplifier in, the form of an oblong chamber having a sound inlet near conolda'l, and fu'rc'ated its center,'"said chamber in'one direction from said inlet being open, and'in the other direction bein of restricted and convergent form Wit 1: a plurality'tif open tipp'e'cl branches or ruraltions having removable closure means.

Signed at Chicago this" 24th day of February,l 920.

WALTER F. nuHNoW;

of flaring form and 

